Phenomenon Filamentous Bacteria - ACAT

Phenomenon Filamentous Bacteria

It seems that 30 different filamentous bacteria species are just waiting to "sabotage" the
uncomplaining processing of wastewater treatment plants. To prevent them from doing
this, they first have to be positively identified under the microscope!

Agglomerate of filaments

Filamentous bacteria in the aeration tank are Floating and bulking sludge
a problem for every sewage treatment plant.
First hints are confirmed by laboratory tests of Index values of more than
the treatment plant: Sludge settling is going 150ml/g set off alarm: Bulking
from bad to worse, the discharge values are sludge exists!
deteriorating rapidly.
There are about 30 different filaments; in
On closer examination it turns out quickly that sewage treatment plants usually Microthrix
floating sludge has already settled in the aera- parvicella, type 021N and type 0041/0675
tion tank. It continues to spread slowly and occur.
suddenly sludge index values exceed to more Due to the very long filaments, which grow
than 150 ml / g. This means bulking sludge mainly from the flake but may also arise in-
exists already! How could it happen? And side the flock (agglomeration) the surface of
from where do floating and bulking sludge the activated sludge flock is greatly enlarged.
come from? Now the flake can reach the water surface
more easily and thus have a negative impact
The answer is as simple as it is unpleasant: on sedimentation.
Filamentous bacteria are at work.

AUTHOR: Anita Landstetter Article from: inside acat 1/2005, page 1 of 3

Phenomenon Filamentous Bacteria

Usually the reason for the "unstoppable" Article from: inside acat 1/2005, page 2 of 3
growth of filaments is the hydrophobic (wa-
ter-repellent) surface of the bacteria, which
finally leads to the flotation of the activated
sludge.
Responsible for the usually compact foam
formation are surface-active substances,
which are excreted by the filaments. As the
exact causes differ from filament to filament,
a microscopic examination of the activated
sludge is inevitable.
Only if the culprits, namely the exact type of
filamentous bacteria of the „sewage treat-
ment plants infarct ", are identified, they can
be controlled effectively and their growth can
be prevented in the long term.

Control Measures
Microscopic examination of filamentous bac-
teria and the targeted use of PAX 18

Causes of an excess of filamentous bacteria
are scum, foam and bulking sludge formation.
They modify the natural balance in the aera-
tion tank and cause serious disruptions of the
cleaning performance of the treatment plant.
If you want to efficiently get to grips” with the
bacteria they have to be identified first. Sam-
ples from the activated sludge are taken and
examined under a microscope. Usually the
microscopic analysis of the filamentous bacte-
ria is carried out as follows:
First, a live preparation of the activated sludge
is taken with 100x, 400x and finally 1000x
magnification under the microscope to de-

AUTHOR: Anita Landstetter

Phenomenon Filamentous Bacteria

termine the morphological properties of the The most common cause of the filamentous
flocks and filaments. bacteria and source of scum is Microthrix par-
vicella, which also can be controlled by the
For the precise identification of the individual targeted use of PAX 18. The result of the
filaments a "Gram" and a "Neisser stain" is treatment is astonishing: soon the sludge has
made. The determination is carried out in ac- its usual compact structure, the settling prop-
cordance with specified identification keys erties regenerate and they are recovered in-
from the relevant literature and with a great stantly.
deal of experience. If the filamentous bacteria
are clearly identified, one can start with con- Thanks to PAX 18 the load of filamentous bac-
trol measures. To solve the problems arising teria type Microthrix parvicella is a thing of
from certain filaments the use of various the past as well as the consequences they
chemicals is essential. But also the modifica- caused: scum, foam, and bulking sludge.
tion or adaptation of sludge treatment is part
of a successful control of filamentous bacte- Control of the sewage treatment plant killer
ria. Microthrix parvicella, with PAX 18

AUTHOR: Anita Landstetter Article from: inside acat 1/2005, page 3 of 3